NORD Drivesystems BU0050 - Manual (Page 63)

2.5 Modbus RTU: Function codes
BU 0050 GB-3111 Subject to technical amendments 63
2.5.1 01h Read Coil
This function enables the readout of inverter bits. The addresses of the bits are listed in the "Coil List".
Master

Slave Slave

Master
Function Code 1 Byte 0x01 Function Code 1 Byte 0x01
Start address 2 Byte 0x0000 to 0x000F Number of bytes 1 Byte 1 to 2
Number of bits 2 Byte 1 to 16 Status of bits n Byte
Example:
4 bits are queries from the address 0x0008 (Bus OUT bits 1 to 4). The bus OUT bits 1 and 2 are High and the
other two bits are Low.
Query (Master

Slave) Response (Slave

Master)
Address 0x08 Address 0x08
Function Code 0x01 Function Code 0x01
Start address High 0x00 Number of bytes 0x01
Start address Low 0x08 Status of Coils 0x03
Number of High Coils 0x00 CRC High 0x12
Number of Low Coils 0x04 CRC Low 0x15
CRC High 0xBC
CRC Low 0x92
2.5.2 05h Write Single Coils
Writes a single 1Bit value The addresses of the bits are listed in the Coil List.
The value 0x0000 is written if a bit is to be deleted. 0xFF00 is written if the bit is to be set.
Master

Slave Slave

Master
Function Code 1 Byte 0x05 Function Code 1 Byte 0x05
Address 2 Byte 0x0000 to 0x0007 Address 2 Byte 0x0000 to 0x0007
Coil value 2 Byte 0x0000 or 0xFF00 Coil value 2 Byte 0x0000 or 0xFF00
Example:
Bus IN Bit 2 is set to the address 0x0001.
Query (Master

Slave) Response (Slave

Master)
Address 0x08 Address 0x08
Function Code 0x05 Function Code 0x05
Address High 0x00 Address High 0x00
Address Low 0x01 Address Low 0x01
Coil value High 0xFF Coil value High 0xFF
Coil value Low 0x00 Coil value Low 0x00
CRC High 0xDD CRC High 0xDD
CRC Low 0x63 CRC Low 0x63